The present invention relates to a storage system for storing data used by a computer.
In recent years, the amount of data handled by computers has increased dramatically, and hence storage devices for storing data are increasing in capacity. At the same time, large storage systems comprising a plurality of disk devices are being designed to store large volumes of data in an aggregated fashion, rather than dispersing these large volumes of data for storage in a large number of small storage devices.
For example, a storage system disclosed in Japanese Unexamined Patent Application Publication 2003-242039 comprises a plurality of physical devices, and manages storage regions constituted by these physical devices as logical devices. A host computer connected to the storage system can access a logical device by specifying a port ID (a WWN (World Wide Name) for identifying a port uniquely) and a LUN (Logical Unit Number) corresponding to the logical device.
Note that hereafter, a device that is specified by a port ID and a LUN, and recognized as a subject of access from a host computer, will be referred to as a target device.